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<div class="title">demo_imi_pq.cpp</div>  </div>
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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">/**</span></div>
<div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment"> * Copyright (c) 2015-present, Facebook, Inc.</span></div>
<div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment"> * All rights reserved.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment"> *</span></div>
<div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment"> * This source code is licensed under the BSD+Patents license found in the</span></div>
<div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment"> * LICENSE file in the root directory of this source tree.</span></div>
<div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;<span class="comment"> */</span></div>
<div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;</div>
<div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="comment">// Copyright 2004-present Facebook. All Rights Reserved</span></div>
<div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;</div>
<div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;</div>
<div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;<span class="preprocessor">#include &lt;cmath&gt;</span></div>
<div class="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="preprocessor">#include &lt;cstdio&gt;</span></div>
<div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="preprocessor">#include &lt;cstdlib&gt;</span></div>
<div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;</div>
<div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="preprocessor">#include &lt;sys/time.h&gt;</span></div>
<div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;</div>
<div class="line"><a name="l00018"></a><span class="lineno">   18</span>&#160;</div>
<div class="line"><a name="l00019"></a><span class="lineno">   19</span>&#160;<span class="preprocessor">#include &lt;faiss/IndexPQ.h&gt;</span></div>
<div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="preprocessor">#include &lt;faiss/IndexIVFPQ.h&gt;</span></div>
<div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;<span class="preprocessor">#include &lt;faiss/IndexFlat.h&gt;</span></div>
<div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;<span class="preprocessor">#include &lt;faiss/index_io.h&gt;</span></div>
<div class="line"><a name="l00023"></a><span class="lineno">   23</span>&#160;</div>
<div class="line"><a name="l00024"></a><span class="lineno">   24</span>&#160;<span class="keywordtype">double</span> elapsed ()</div>
<div class="line"><a name="l00025"></a><span class="lineno">   25</span>&#160;{</div>
<div class="line"><a name="l00026"></a><span class="lineno">   26</span>&#160;    <span class="keyword">struct </span>timeval tv;</div>
<div class="line"><a name="l00027"></a><span class="lineno">   27</span>&#160;    gettimeofday (&amp;tv, <span class="keyword">nullptr</span>);</div>
<div class="line"><a name="l00028"></a><span class="lineno">   28</span>&#160;    <span class="keywordflow">return</span>  tv.tv_sec + tv.tv_usec * 1e-6;</div>
<div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;}</div>
<div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;</div>
<div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;</div>
<div class="line"><a name="l00032"></a><span class="lineno">   32</span>&#160;<span class="keywordtype">int</span> main ()</div>
<div class="line"><a name="l00033"></a><span class="lineno">   33</span>&#160;{</div>
<div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;    <span class="keywordtype">double</span> t0 = elapsed();</div>
<div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;</div>
<div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;    <span class="comment">// dimension of the vectors to index</span></div>
<div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;    <span class="keywordtype">int</span> d = 64;</div>
<div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;</div>
<div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;    <span class="comment">// size of the database we plan to index</span></div>
<div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;    <span class="keywordtype">size_t</span> nb = 1000 * 1000;</div>
<div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;    <span class="keywordtype">size_t</span> add_bs = 10000; <span class="comment">// # size of the blocks to add</span></div>
<div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;</div>
<div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;    <span class="comment">// make a set of nt training vectors in the unit cube</span></div>
<div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;    <span class="comment">// (could be the database)</span></div>
<div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;    <span class="keywordtype">size_t</span> nt = 100 * 1000;</div>
<div class="line"><a name="l00046"></a><span class="lineno">   46</span>&#160;</div>
<div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;    <span class="comment">//---------------------------------------------------------------</span></div>
<div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;    <span class="comment">// Define the core quantizer</span></div>
<div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;    <span class="comment">// We choose a multiple inverted index for faster training with less data</span></div>
<div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;    <span class="comment">// and because it usually offers best accuracy/speed trade-offs</span></div>
<div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;    <span class="comment">// We here assume that its lifespan of this coarse quantizer will cover the</span></div>
<div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;    <span class="comment">// lifespan of the inverted-file quantizer IndexIVFFlat below</span></div>
<div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;    <span class="comment">// With dynamic allocation, one may give the responsability to free the</span></div>
<div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;    <span class="comment">// quantizer to the inverted-file index (with attribute do_delete_quantizer)</span></div>
<div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;    <span class="comment">// Note: a regular clustering algorithm would be defined as:</span></div>
<div class="line"><a name="l00058"></a><span class="lineno">   58</span>&#160;    <span class="comment">//       faiss::IndexFlatL2 coarse_quantizer (d);</span></div>
<div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;    <span class="comment">// Use nhash=2 subquantizers used to define the product coarse quantizer</span></div>
<div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;    <span class="comment">// Number of bits: we will have 2^nbits_coarse centroids per subquantizer</span></div>
<div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;    <span class="comment">//                 meaning (2^12)^nhash distinct inverted lists</span></div>
<div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00064"></a><span class="lineno">   64</span>&#160;    <span class="comment">// The parameter bytes_per_code is determined by the memory</span></div>
<div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;    <span class="comment">// constraint, the dataset will use nb * (bytes_per_code + 8)</span></div>
<div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;    <span class="comment">// bytes.</span></div>
<div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00068"></a><span class="lineno">   68</span>&#160;    <span class="comment">// The parameter nbits_subq is determined by the size of the dataset to index.</span></div>
<div class="line"><a name="l00069"></a><span class="lineno">   69</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00070"></a><span class="lineno">   70</span>&#160;    <span class="keywordtype">size_t</span> nhash = 2;</div>
<div class="line"><a name="l00071"></a><span class="lineno">   71</span>&#160;    <span class="keywordtype">size_t</span> nbits_subq = 9;</div>
<div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;    <span class="keywordtype">size_t</span> ncentroids = 1 &lt;&lt; (nhash * nbits_subq);  <span class="comment">// total # of centroids</span></div>
<div class="line"><a name="l00073"></a><span class="lineno">   73</span>&#160;    <span class="keywordtype">int</span> bytes_per_code = 16;</div>
<div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;</div>
<div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;    <a class="code" href="structfaiss_1_1MultiIndexQuantizer.html">faiss::MultiIndexQuantizer</a> coarse_quantizer (d, nhash, nbits_subq);</div>
<div class="line"><a name="l00076"></a><span class="lineno">   76</span>&#160;</div>
<div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;    printf (<span class="stringliteral">&quot;IMI (%ld,%ld): %ld virtual centroids (target: %ld base vectors)&quot;</span>,</div>
<div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;            nhash, nbits_subq, ncentroids, nb);</div>
<div class="line"><a name="l00079"></a><span class="lineno">   79</span>&#160;</div>
<div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;    <span class="comment">// the coarse quantizer should not be dealloced before the index</span></div>
<div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;    <span class="comment">// 4 = nb of bytes per code (d must be a multiple of this)</span></div>
<div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;    <span class="comment">// 8 = nb of bits per sub-code (almost always 8)</span></div>
<div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;    <a class="code" href="namespacefaiss.html#afd12191c638da74760ff397cf319752c">faiss::MetricType</a> metric = faiss::METRIC_L2; <span class="comment">// can be METRIC_INNER_PRODUCT</span></div>
<div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;    <a class="code" href="structfaiss_1_1IndexIVFPQ.html">faiss::IndexIVFPQ</a> index (&amp;coarse_quantizer, d, ncentroids, bytes_per_code, 8);</div>
<div class="line"><a name="l00085"></a><span class="lineno">   85</span>&#160;    index.quantizer_trains_alone = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00086"></a><span class="lineno">   86</span>&#160;</div>
<div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;    <span class="comment">// define the number of probes. 2048 is for high-dim, overkill in practice</span></div>
<div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;    <span class="comment">// Use 4-1024 depending on the trade-off speed accuracy that you want</span></div>
<div class="line"><a name="l00089"></a><span class="lineno">   89</span>&#160;    index.nprobe = 2048;</div>
<div class="line"><a name="l00090"></a><span class="lineno">   90</span>&#160;</div>
<div class="line"><a name="l00091"></a><span class="lineno">   91</span>&#160;</div>
<div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;    { <span class="comment">// training.</span></div>
<div class="line"><a name="l00093"></a><span class="lineno">   93</span>&#160;</div>
<div class="line"><a name="l00094"></a><span class="lineno">   94</span>&#160;        <span class="comment">// The distribution of the training vectors should be the same</span></div>
<div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;        <span class="comment">// as the database vectors. It could be a sub-sample of the</span></div>
<div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;        <span class="comment">// database vectors, if sampling is not biased. Here we just</span></div>
<div class="line"><a name="l00097"></a><span class="lineno">   97</span>&#160;        <span class="comment">// randomly generate the vectors.</span></div>
<div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;</div>
<div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Generating %ld vectors in %dD for training\n&quot;</span>,</div>
<div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;                elapsed() - t0, nt, d);</div>
<div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;</div>
<div class="line"><a name="l00102"></a><span class="lineno">  102</span>&#160;        std::vector &lt;float&gt; trainvecs (nt * d);</div>
<div class="line"><a name="l00103"></a><span class="lineno">  103</span>&#160;        <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> i = 0; i &lt; nt; i++) {</div>
<div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;            <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> j = 0; j &lt; d; j++) {</div>
<div class="line"><a name="l00105"></a><span class="lineno">  105</span>&#160;                trainvecs[i * d + j] = drand48();</div>
<div class="line"><a name="l00106"></a><span class="lineno">  106</span>&#160;            }</div>
<div class="line"><a name="l00107"></a><span class="lineno">  107</span>&#160;        }</div>
<div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;</div>
<div class="line"><a name="l00109"></a><span class="lineno">  109</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Training the index\n&quot;</span>, elapsed() - t0);</div>
<div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;        index.verbose = <span class="keyword">true</span>;</div>
<div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;        index.train (nt, trainvecs.data());</div>
<div class="line"><a name="l00112"></a><span class="lineno">  112</span>&#160;    }</div>
<div class="line"><a name="l00113"></a><span class="lineno">  113</span>&#160;</div>
<div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;    <span class="comment">// the index can be re-loaded later with</span></div>
<div class="line"><a name="l00115"></a><span class="lineno">  115</span>&#160;    <span class="comment">// faiss::Index * idx = faiss::read_index(&quot;/tmp/trained_index.faissindex&quot;);</span></div>
<div class="line"><a name="l00116"></a><span class="lineno">  116</span>&#160;    faiss::write_index(&amp;index, <span class="stringliteral">&quot;/tmp/trained_index.faissindex&quot;</span>);</div>
<div class="line"><a name="l00117"></a><span class="lineno">  117</span>&#160;</div>
<div class="line"><a name="l00118"></a><span class="lineno">  118</span>&#160;    <span class="keywordtype">size_t</span> nq;</div>
<div class="line"><a name="l00119"></a><span class="lineno">  119</span>&#160;    std::vector&lt;float&gt; queries;</div>
<div class="line"><a name="l00120"></a><span class="lineno">  120</span>&#160;</div>
<div class="line"><a name="l00121"></a><span class="lineno">  121</span>&#160;    { <span class="comment">// populating the database</span></div>
<div class="line"><a name="l00122"></a><span class="lineno">  122</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Building a dataset of %ld vectors to index\n&quot;</span>,</div>
<div class="line"><a name="l00123"></a><span class="lineno">  123</span>&#160;                elapsed() - t0, nb);</div>
<div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;</div>
<div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;        std::vector &lt;float&gt; database (nb * d);</div>
<div class="line"><a name="l00126"></a><span class="lineno">  126</span>&#160;        std::vector &lt;long&gt; ids (nb);</div>
<div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;        <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> i = 0; i &lt; nb; i++) {</div>
<div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;            <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> j = 0; j &lt; d; j++) {</div>
<div class="line"><a name="l00129"></a><span class="lineno">  129</span>&#160;                database[i * d + j] = drand48();</div>
<div class="line"><a name="l00130"></a><span class="lineno">  130</span>&#160;            }</div>
<div class="line"><a name="l00131"></a><span class="lineno">  131</span>&#160;            ids[i] = 8760000000L + i;</div>
<div class="line"><a name="l00132"></a><span class="lineno">  132</span>&#160;        }</div>
<div class="line"><a name="l00133"></a><span class="lineno">  133</span>&#160;</div>
<div class="line"><a name="l00134"></a><span class="lineno">  134</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Adding the vectors to the index\n&quot;</span>, elapsed() - t0);</div>
<div class="line"><a name="l00135"></a><span class="lineno">  135</span>&#160;</div>
<div class="line"><a name="l00136"></a><span class="lineno">  136</span>&#160;        <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> begin = 0; begin &lt; nb; begin += add_bs) {</div>
<div class="line"><a name="l00137"></a><span class="lineno">  137</span>&#160;            <span class="keywordtype">size_t</span> end = std::min (begin + add_bs, nb);</div>
<div class="line"><a name="l00138"></a><span class="lineno">  138</span>&#160;            index.add_with_ids (end - begin,</div>
<div class="line"><a name="l00139"></a><span class="lineno">  139</span>&#160;                                database.data() + d * begin,</div>
<div class="line"><a name="l00140"></a><span class="lineno">  140</span>&#160;                                ids.data() + begin);</div>
<div class="line"><a name="l00141"></a><span class="lineno">  141</span>&#160;        }</div>
<div class="line"><a name="l00142"></a><span class="lineno">  142</span>&#160;</div>
<div class="line"><a name="l00143"></a><span class="lineno">  143</span>&#160;        <span class="comment">// remember a few elements from the database as queries</span></div>
<div class="line"><a name="l00144"></a><span class="lineno">  144</span>&#160;        <span class="keywordtype">int</span> i0 = 1234;</div>
<div class="line"><a name="l00145"></a><span class="lineno">  145</span>&#160;        <span class="keywordtype">int</span> i1 = 1244;</div>
<div class="line"><a name="l00146"></a><span class="lineno">  146</span>&#160;</div>
<div class="line"><a name="l00147"></a><span class="lineno">  147</span>&#160;        nq = i1 - i0;</div>
<div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;        queries.resize (nq * d);</div>
<div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;        <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = i0; i &lt; i1; i++) {</div>
<div class="line"><a name="l00150"></a><span class="lineno">  150</span>&#160;            <span class="keywordflow">for</span> (<span class="keywordtype">int</span> j = 0; j &lt; d; j++) {</div>
<div class="line"><a name="l00151"></a><span class="lineno">  151</span>&#160;                queries [(i - i0) * d  + j] = database [i * d + j];</div>
<div class="line"><a name="l00152"></a><span class="lineno">  152</span>&#160;            }</div>
<div class="line"><a name="l00153"></a><span class="lineno">  153</span>&#160;        }</div>
<div class="line"><a name="l00154"></a><span class="lineno">  154</span>&#160;    }</div>
<div class="line"><a name="l00155"></a><span class="lineno">  155</span>&#160;</div>
<div class="line"><a name="l00156"></a><span class="lineno">  156</span>&#160;    <span class="comment">// A few notes on the internal format of the index:</span></div>
<div class="line"><a name="l00157"></a><span class="lineno">  157</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00158"></a><span class="lineno">  158</span>&#160;    <span class="comment">// - the positing lists for PQ codes are index.codes, which is a</span></div>
<div class="line"><a name="l00159"></a><span class="lineno">  159</span>&#160;    <span class="comment">//    std::vector &lt; std::vector&lt;uint8_t&gt; &gt;</span></div>
<div class="line"><a name="l00160"></a><span class="lineno">  160</span>&#160;    <span class="comment">//   if n is the length of posting list #i, codes[i] has length bytes_per_code * n</span></div>
<div class="line"><a name="l00161"></a><span class="lineno">  161</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00162"></a><span class="lineno">  162</span>&#160;    <span class="comment">// - the corresponding ids are stored in index.ids</span></div>
<div class="line"><a name="l00163"></a><span class="lineno">  163</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00164"></a><span class="lineno">  164</span>&#160;    <span class="comment">// - given a vector float *x, finding which k centroids are</span></div>
<div class="line"><a name="l00165"></a><span class="lineno">  165</span>&#160;    <span class="comment">//   closest to it (ie to find the nearest neighbors) can be done with</span></div>
<div class="line"><a name="l00166"></a><span class="lineno">  166</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00167"></a><span class="lineno">  167</span>&#160;    <span class="comment">//   long *centroid_ids = new long[k];</span></div>
<div class="line"><a name="l00168"></a><span class="lineno">  168</span>&#160;    <span class="comment">//   float *distances = new float[k];</span></div>
<div class="line"><a name="l00169"></a><span class="lineno">  169</span>&#160;    <span class="comment">//   index.quantizer-&gt;search (1, x, k, dis, centroids_ids);</span></div>
<div class="line"><a name="l00170"></a><span class="lineno">  170</span>&#160;    <span class="comment">//</span></div>
<div class="line"><a name="l00171"></a><span class="lineno">  171</span>&#160;</div>
<div class="line"><a name="l00172"></a><span class="lineno">  172</span>&#160;    faiss::write_index(&amp;index, <span class="stringliteral">&quot;/tmp/populated_index.faissindex&quot;</span>);</div>
<div class="line"><a name="l00173"></a><span class="lineno">  173</span>&#160;</div>
<div class="line"><a name="l00174"></a><span class="lineno">  174</span>&#160;    { <span class="comment">// searching the database</span></div>
<div class="line"><a name="l00175"></a><span class="lineno">  175</span>&#160;        <span class="keywordtype">int</span> k = 5;</div>
<div class="line"><a name="l00176"></a><span class="lineno">  176</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Searching the %d nearest neighbors &quot;</span></div>
<div class="line"><a name="l00177"></a><span class="lineno">  177</span>&#160;                <span class="stringliteral">&quot;of %ld vectors in the index\n&quot;</span>,</div>
<div class="line"><a name="l00178"></a><span class="lineno">  178</span>&#160;                elapsed() - t0, k, nq);</div>
<div class="line"><a name="l00179"></a><span class="lineno">  179</span>&#160;</div>
<div class="line"><a name="l00180"></a><span class="lineno">  180</span>&#160;        std::vector&lt;faiss::Index::idx_t&gt; nns (k * nq);</div>
<div class="line"><a name="l00181"></a><span class="lineno">  181</span>&#160;        std::vector&lt;float&gt;               dis (k * nq);</div>
<div class="line"><a name="l00182"></a><span class="lineno">  182</span>&#160;</div>
<div class="line"><a name="l00183"></a><span class="lineno">  183</span>&#160;        index.search (nq, queries.data(), k, dis.data(), nns.data());</div>
<div class="line"><a name="l00184"></a><span class="lineno">  184</span>&#160;</div>
<div class="line"><a name="l00185"></a><span class="lineno">  185</span>&#160;        printf (<span class="stringliteral">&quot;[%.3f s] Query results (vector ids, then distances):\n&quot;</span>,</div>
<div class="line"><a name="l00186"></a><span class="lineno">  186</span>&#160;                elapsed() - t0);</div>
<div class="line"><a name="l00187"></a><span class="lineno">  187</span>&#160;</div>
<div class="line"><a name="l00188"></a><span class="lineno">  188</span>&#160;        <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i &lt; nq; i++) {</div>
<div class="line"><a name="l00189"></a><span class="lineno">  189</span>&#160;            printf (<span class="stringliteral">&quot;query %2d: &quot;</span>, i);</div>
<div class="line"><a name="l00190"></a><span class="lineno">  190</span>&#160;            <span class="keywordflow">for</span> (<span class="keywordtype">int</span> j = 0; j &lt; k; j++) {</div>
<div class="line"><a name="l00191"></a><span class="lineno">  191</span>&#160;                printf (<span class="stringliteral">&quot;%7ld &quot;</span>, nns[j + i * k]);</div>
<div class="line"><a name="l00192"></a><span class="lineno">  192</span>&#160;            }</div>
<div class="line"><a name="l00193"></a><span class="lineno">  193</span>&#160;            printf (<span class="stringliteral">&quot;\n     dis: &quot;</span>);</div>
<div class="line"><a name="l00194"></a><span class="lineno">  194</span>&#160;            <span class="keywordflow">for</span> (<span class="keywordtype">int</span> j = 0; j &lt; k; j++) {</div>
<div class="line"><a name="l00195"></a><span class="lineno">  195</span>&#160;                printf (<span class="stringliteral">&quot;%7g &quot;</span>, dis[j + i * k]);</div>
<div class="line"><a name="l00196"></a><span class="lineno">  196</span>&#160;            }</div>
<div class="line"><a name="l00197"></a><span class="lineno">  197</span>&#160;            printf (<span class="stringliteral">&quot;\n&quot;</span>);</div>
<div class="line"><a name="l00198"></a><span class="lineno">  198</span>&#160;        }</div>
<div class="line"><a name="l00199"></a><span class="lineno">  199</span>&#160;    }</div>
<div class="line"><a name="l00200"></a><span class="lineno">  200</span>&#160;    <span class="keywordflow">return</span> 0;</div>
<div class="line"><a name="l00201"></a><span class="lineno">  201</span>&#160;}</div>
<div class="ttc" id="structfaiss_1_1IndexIVFPQ_html"><div class="ttname"><a href="structfaiss_1_1IndexIVFPQ.html">faiss::IndexIVFPQ</a></div><div class="ttdef"><b>Definition:</b> <a href="IndexIVFPQ_8h_source.html#l00029">IndexIVFPQ.h:29</a></div></div>
<div class="ttc" id="structfaiss_1_1MultiIndexQuantizer_html"><div class="ttname"><a href="structfaiss_1_1MultiIndexQuantizer.html">faiss::MultiIndexQuantizer</a></div><div class="ttdef"><b>Definition:</b> <a href="IndexPQ_8h_source.html#l00135">IndexPQ.h:135</a></div></div>
<div class="ttc" id="namespacefaiss_html_afd12191c638da74760ff397cf319752c"><div class="ttname"><a href="namespacefaiss.html#afd12191c638da74760ff397cf319752c">faiss::MetricType</a></div><div class="ttdeci">MetricType</div><div class="ttdoc">Some algorithms support both an inner product version and a L2 search version. </div><div class="ttdef"><b>Definition:</b> <a href="Index_8h_source.html#l00043">Index.h:43</a></div></div>
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